Method for examining the inner surface of a hollow member

ABSTRACT

A method of examining the inner surface of a hollow member is disclosed. The method includes inserting a test body into the hollow member and pressing the test body against the inner surface of the hollow member at a temperature sufficient to cause at least the surface of the test body to deform whereby a relief of the inner surface of the hollow member is obtained. An apparatus for performing the method of the invention is also disclosed. The apparatus includes the test body and a pressure generating device for developing the pressure needed to press the test body against the inner surface of the hollow member.

United States Patent. [191 Michel m1] 3,800,598 [451 1 Apr. 2, 1974 7METHOD FOR EXAMINING THE INNER SURFACE OF A HOLLOW MEMBER [75] Inventor:Eberhard Michel, Boxdorf,

Germany [73] Assignee: Siemens Aktiengesellschaft, Munich,

Germany [22] Filed: Nov. 9, I972 211 App]. Nb; 304,920

[30] Foreign Application Priority Data Nov. I0, 1971 Germany 2155812 52US. Cl. 73/104, 73/167 [51] Int. Cl. G01n 19/08 [58] Field of Search73/104, 105, 167

[56] References Cited UNITED STATES PATENTS 3,662,592 5/1972 -Geisler73/l04 FOREIGN PATENTS OR APPLICATIONS 977,502 12/1964 Great Britain73/104 Primary ExaminerS. Clement Swisher Attorney, Agent, orFirm--I(enyon & Kenyon Reilly Carr & Chapin 5 7] ABSTRACT A method ofexamining the inner surface of a hollow member is disclosed. The methodincludes inserting a test body into the hollow member and pressing thetest body against the inner surface of the hollow member at atemperature sufficient to cause at least the surface of the test body to'defonn whereby a relief of the inner surface of the hollow member isobtained.

An apparatus for performing the method of the invention is alsodisclosed. The apparatus includes the test body and a pressuregenerating device for developing the pressure needed to press the testbody against the inner surface of the hollow member.

2 Claims, 2 Drawing Figures METHOD FOR EXAMINING THE INNER SURFACE OF AHOLLOW MEMBER BACKGROUND OF THE INVENTION The invention relates to amethod of examining the inside surface of a hollow member and anapparatus for performing the method.

For evaluating the quality of a hollow member such as a tube, thecondition of the surface of the tube among other things, is of greatimportance. While it is easy to judge the exterior surface, the interiorsurface can in general be evaluated only inadequately. This problemarises, for example, when the condition of the heat exchanger pipes insteam generators for water pressure reactors must be examined in theevent a leak occurs.

SUMMARY OF THE INVENTION It is an object of the invention to provide amethod of examining the inner surface of a hollow member. It is anotherobject of the invention to provide such a method for obtaining a reliefof the inner surface of a hollow body such as a tube or the like.

It is still another object of the invention to provide an apparatus forperforming the method of the invention.

The method includes as a feature the step of inserting a test body intothe hollow member and then pressing the test body against the innersurface of the hollow member at a temperature sufficient to cause atleast the surface of the test body to deform whereby a relief of theinner surface of the hollow member is obtained.

The surface of the test body can plastically deform so that an image inrelief fashion is embossed in the surface of the test body. This permitsan observer to evaluate the condition of the inside surface of thehollow member. The test body can be pressed against the hollow member bymeans of a warm fluid such as warm compressed air or a warm liquid underpressure.

The apparatus for examining the inner surface of a hollow memberincludes as a feature a hollow test body which has an outer surface andis insertable into the hollow member. Pressure means in the form of apressure generating device is connected to the hollow test body forapplying a pressure thereto to press the outer surface thereof tightlyagainst the inner surface of the hollow member at a temperaturesufficient to cause at least the outer surface of the test body todeform an amount sufficient to form a relief of the inner surface of thehollow member therein. The pressure generating equipment can fill thetest body with a warm medium or cause the warm medium to flow throughthe test body. Or, the hollow member to be examined can be heated forobtaining the required temperature.

According to another feature of the invention, the test body can be madeof plastic. It is preferable to use a test body which is hollow and isfitted to the inside surface of the hollow member as well as to whichpressure can be applied. If the hollow member is a tube, it isadvantageous to use a hose as the test body.

By means of the plastic deformation of the surface of the test body, areproduction of the inside surface of the hollow member is obtained. If,for example, the inside surface of a hollow member in the form ofa tubeis imaged in relief on the outside surface of a hose as the test body,the inside surface can be evaluated without difficulty. Even with pooraccessibility, a defect can be made visible if it is situated on theinside of the tube, or else, it is possible to show that the damage ison the outside of the tube. With the method and apparatus according tothe invention, a rapid, inexpensive and simple test of the entiresurface of a hollow body, especially of the inside surface, is possible.The examination is extremely reliable. It is also important that it canbe applied to interiors of hollow members of irregular v shape, forexample, to bent tubes.

Although the invention is illustrated and described herein as a methodand apparatus for examining the inner surface of a hollow member, it isnevertheless not intended to be limited to the details shown, sincevarious modifications may be made therein within the scope and the rangeof the claims. The invention, however, together with additional objectsand advantages will be best understood from the following descriptionand in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENTS OF THE INVENTION FIG. 1 shows a cross-section of a tube 1 tobe examined into which a test body in the form of a flexible hose 2 hasbeen introduced. The hose 2 is connected by a connecting line 3 with apressure-generating device 4 which serves as a pressure means forapplying pressure to the test body. A source of compressed air or asource ofa liquid such as water under pressure can be used as thepressure-generating device 4. The pressure means thus comprises fluidsupply means for supplying fluid to the test body to fill the same underpressure.

The outside diameter of the hose or hose-like bag 2 introduced into thetube 1 is somewhat smaller than the inside diameter of the tube. Thehose 2 is filled by the pressure-generating device with a medium atdefined pressure.

According to another embodiment shown in FIG. 2, the pressure-developingmedium can flow through the hose 2. A closed circuit can be establishedby utilizing a connecting line 3a. The hose 2 is firmly pressed againstthe inside wall of the tube. The pressuredeveloping medium is heated toa temperature at which the material of the hose is plastically deformed.Or, the tube can be heated to the temperature required for deformationby means of a separate heating arrangement, for example, by heatingmeans in the form of an induction coil 5 as in the case where the tube 1is made of steel. As a hose material, a plastic such as softpolyvinylchloride (PVC) is particularly well suited, because when coldit is inherently elastically deformable and this permits the hose to bepulled from the inside of the tube and inspected. At the requiredtemperature and pressure, the inside surface of the tube l is imagedexactly on the surface of the hose. Thereafter, with cooling, thisplastic is changed to its normal elastically deformable, non-moldableform.

A straight section of tube 1 is shown in the FIGS. The test according tothe invention of the inside surface of the tube can of course also beperformed in the case of a bent tube wherein a flexible hose or bag isused as the test body.

What is claimed is:

l. A method for examining the inner surface of a tubular member byinserting an inflatable tubular test body in said member and inflatingsaid body, and then after removing said body from said member,inspecting the surface of said body; wherein the improvement comprisesinserting in said member a tubular test body that is inflatable and madeof a plastic that is plastically moldable under pressure and can 'bechanged to an elastically deformable form, inflating said plastic bodywhile it is plastically moldable so its surface is molded with a reliefof the inner surface of said member, and thereafter changing saidplastic of said plastic body to its said elastically deformable form sothat said plastic body can be removed from said member for inspection ofthe relief obtained on the surface of the plastic test body.

2. The method of claim 1 in which said plastic is soft polyvinylchlorideand is heated to its plastically moldable form while said test body isinflated, and is by cooling changed to its normal elastically deformableform. =l=

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, ,59D t d p i 197 Invent v Eberhard Michel It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In the Foreign Application Priority Data change the file number of theGerman application upon which the claim fc priority, is based from"2155812" to P 21 55 812.3--

Signed and sealed this gthfiay of July 1974.

(SEAL) Attest:

McCOY GIBSON, JR. C. MARSHALL DANN Attestlng Officer Commissioner ofPatents FORM Po-wso (10-59) USCOMM'DC U0376-P59 U.S. GOVERNMENT PRINTINGOFFICE l9! 0-866-334,

1. A methoD for examining the inner surface of a tubular member byinserting an inflatable tubular test body in said member and inflatingsaid body, and then after removing said body from said member,inspecting the surface of said body; wherein the improvement comprisesinserting in said member a tubular test body that is inflatable and madeof a plastic that is plastically moldable under pressure and can bechanged to an elastically deformable form, inflating said plastic bodywhile it is plastically moldable so its surface is molded with a reliefof the inner surface of said member, and thereafter changing saidplastic of said plastic body to its said elastically deformable form sothat said plastic body can be removed from said member for inspection ofthe relief obtained on the surface of the plastic test body.
 2. Themethod of claim 1 in which said plastic is soft polyvinylchloride and isheated to its plastically moldable form while said test body isinflated, and is by cooling changed to its normal elastically deformableform.